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Show 158 HETEROSTY LED TRIMORPHIC PLANTS. CHAP. IV. by bees with pollen from their own stamens produced numerous capsules containing on an average 21·5 seeds. Mid-styled jorm.-Twenty-four flowers legiti1nately fertilised by the stamens of corresponding length, borne by the long and short-styled forms, yielded 96 (probably 100) per cent. of capsules, which contained (excluding one capsule with 12 seeds) on an average 117 ·2 seeds. Fifteen mid-styled flowers fertilised illegitimately by the longest stamens of the short-sty led form yielded 93 per cent. of capsules, which (excluding four capsules with less than 20 seeds) contained on an average 102·8 seeds. Thirteen mid-styled flowers fertilised illegitimately by the mid-length stamens of the long-styled fonn yielded 54 per cent. of capsules, which (excluding one with 19 seeds) contained on an average 60·2 seeds. Twelve mid-styled flowers fertilised illegitimately by their own-form longest stamens yielded 25 per cent. of capsules, which (excluding one with 9 seeds) contained on an average 77·5 seeds. Twelve mid-styled flowers fertilised illegitimately by their own-form . shortest stamens yielded not a single capsule. Short-styled form.-Twen ty-:five flowers fertilised legitimately by the stamens of corresponding length, borne by the long and mid-styled forms, yielded 72 per cent. of capsules, which (excluding one Cttpsule with only 9 seeds) contained on an average 70·8 seeds. Twenty short-styled flowers fertilised illegitimately by the other stamens of the long and mid -sty led forms yielded only two very poor capsules. Twenty short-styled flowers fertilised illegitimately CHAP. IV. LYTHRUM SALIOARIA. 159 by their own stamens yielded only two poor (or perhaps three) capsules. If we take all six legitimate unions together, and all twelve illegitimate unions together, we get the following results :- TABLE 26. Number Number Average Average Number of Nature of Union. of Flowers of Capsules Number of Seeds per fertilised. produced. Seeds per Capsule. Flower fer- tilised. Th~ . six legitimate} 7.5 56 96•29 71•89 un1ons. • • • --- The twelve illegiti-) mate unions • . f 146 36 44·72 11•03 Therefore the fertility of the legitimate unions to that of the illegitimate, as judged by the proportion of the fertilised flowers which yielded capsules, is as 100 to 33 ; and judged by the average number of seeds per capsule, as 100 to 46. From this summary and the several foregoing tables we see that it is only pollen from the longest stamens which can fully fertilise the longest pistil ; only that from the mid-length stamens, the mid-length pistil; and only that from the shortest stamens, the shortest pistil. And now we can comprehend the meaning of the almost exact correspondence in length between the pistil in each form and a set of six stamens in two of' the other forms ; for the stigma of each form is thus rubbed against that part of the insect's body which becomes charged with the proper pollen. It is also evident that the stigma of each form, fertilised in three different ways with pollen from the longest, mid -length, and shortest stamens, is acted on very differently, and conversely that the pollen from • |